Solid oxide fuel cell structure

ABSTRACT

A solid oxide fuel cell structure includes an anode, a cathode arranged oppositely relative to the anode and electrolyte located between the anode and the cathode and at least two air paths each having a distal end provided with a turn and a continuous curve closing the distal end.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from application No. 100114025, filed on Apr. 22, 2011 in the Taiwan Intellectual Property Office.

FIELD OF THE INVENTION

The present invention is related to the structure of solid state electrolyte in a fuel cell structure, and more particularly to a solid oxide fuel cell structure having air paths defined beside the anode and cathode and on two sides of the electrolyte. Each of the air paths has a distal end provided with a turn and a continuous curve to spread stress during manufacture and to prolong its lifespan.

BACKGROUND OF THE INVENTION

A fuel cell (FC) has higher energy conversion rate than the conventional batteries and poses no threat to the environment. Its importance is now playing a vital role in the new energy era.

A fuel cell generally converts chemical energy into electricity through a circuit composed by the cathode, the anode and the electrolyte as well as the potential difference between reducible fuel such as hydrogen and oxide gas such as oxygen to undergo a spontaneously oxidation reduction. The byproduct of this oxidation reduction will be water or carbon dioxide (CO₂) only so that there is no pollution issue to use this kind of reaction.

Based on ion variation and ion conduction differences, a fuel cell generally is categorized to five different types and among which, the solid oxide fuel cell, SOFC, also called ceramic fuel cell, has the highest reaction rate and requires no activator to undergo the reaction. In addition, the SOFC is available for various fuels and the byproduct, steam, during its reaction is good for steam-power generation industry. The conversion rate for this steam-power generation reaches more than 80% efficiency.

During the use of a solid oxide fuel cell, the fuel containing carbon monoxide (CO) and hydrogen (H₂) flows through air paths and diffuses on the surface of the anode. If the distal ends of the air paths are right angles and the fuel in gas type flows through the distal ends, stress at the right angles of the air paths distal ends builds up, which will easily break the distal ends of the air paths due to large concentration of air pressure.

Furthermore, because the electrolyte is sandwiched between the anode and the cathode, while in manufacture, if the distal ends of the air paths are right angles, the distal ends will easy be stress concentrated and eventually cause breakage during curing. Other factors such as differences among material characteristics will too cause the breakage to the distal ends of the air paths during drying and expansion and contraction (cooling process).

As a result of these problems, the most crucial problem to be solved is to create an air path that will disperse the stress both in the manufacture process and in the reaction process.

SUMMARY OF THE INVENTION

The objective of the present invention is to provide a solid oxide fuel cell structure having at least two air paths each having a distal end with a continuous curve closing the distal end such that when gas-typed fuel flows through the continuous curve, the continuous curve can spread stress and thus prolong lifespan of the solid oxide fuel cell.

Another objective of the present invention is to provide a solid oxide fuel cell structure having at least two air paths each provided with a continuous curve so that breakage during manufacturing processes such as drying, sintering and curing can be avoided and the yield of the solid oxide fuel cell is thus high.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a preferred embodiment of the solid oxide fuel cell structure of the present invention;

FIG. 2 is another perspective view of the preferred embodiment of the solid oxide fuel cell structure with a portion of the structure removed; and

FIG. 3 is still a perspective view showing a different embodiment of the solid oxide fuel cell structure of the present invention.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

Hereinafter, embodiments of the present invention will now be described in greater detail with reference to the accompanying drawings.

To achieve aforesaid goals and effects, for thorough understanding, the techniques and structures adopted by the preferred embodiment of the invention is illustrated in detail with its features and functions described as below.

It is well known in the art that a solid oxide fuel cell is generally composed of an anode, a cathode oppositely located relative to the anode and electrolyte sandwiched between the anode and the cathode. In addition, multiple air paths 1 (at least two) are defined along the anode and the cathode to allow reducible fuel such as hydrogen and the like and oxygen to flow therethrough.

With reference to FIGS. 1 and 2, each of the air paths 1 is provided with a distal end 12. Each of the distal ends 12 of the air paths 1 is defined to have a turn 11 and a continuous curve 13 closing the distal end 12. Due to the provision of the continuous curve 13 at the distal end 12 of each of the air paths 1, an outer contour of the distal end 12 is of semi-spherical shape.

The continuous curve 13 includes, but not limited to, a quadric surface, camber, spherical surface or parabolic quadratic surface. The slope of the continuous curve is a continuous value and has no single point.

Based on ion variations and ion conduction differences, a fuel cell generally is categorized to five different types and among which, the solid oxide fuel cell, SOFC, also called ceramic fuel cell, is exemplarily used for the preferred embodiment of the present invention. Because the electrical resistance of the anode, the cathode and the electrolyte are different from one another and increases as the thickness of the material for making each of the anode, the cathode and the electrolyte becomes thicker, the SOFC has the following types, electrolyte supported cell, the cathode supported cell and the anode supported cell. Because the anode has much higher conduction rate than the cathode and the electrolyte, using the anode supported cell will greatly reduce the electrical resistance within the cell. However, manufacture of the thin film used in this kind of solid oxide fuel cell is difficult and a breakthrough in the related technology is required to solve the dilemma.

With reference to FIG. 3, it is noted that the air paths 1 are arranged alternately to have one for the reducible fuel and the other for gas.

It is to be noted that the design of the continuous curve is extremely helpful in spreading the stress when the gas-typed fuel flows to the anode as well as the cathode and diffuses. Furthermore, during manufacture process, the continuous curve is also helpful in spreading the stress caused by the curing processes such as drying and cooling. The outer contour of the distal end of each of the air paths 1 being spherical shape is also helpful in enhancing the strength of the air paths 1.

While various embodiments are discussed herein, it will be understood that they are not intended to limit to these embodiments. On the contrary, the presented embodiments are intended to cover alternatives, modifications and equivalents, which may be included within the spirit and scope of the various embodiments. Furthermore, in this Description of Embodiments, numerous specific details are set forth in order to provide a thorough understanding of embodiments of the present subject matter. However, embodiments may be practiced without these specific details. In other instances, well known steps, procedures, components, and circuits have not been described in detail as not to unnecessarily obscure aspects of the described embodiments. 

1. In a solid oxide fuel cell structure having an anode, a cathode arranged oppositely relative to the anode and electrolyte located between the anode and the cathode, wherein the improvements comprise: at least two air paths each having a distal end provided with a turn and a continuous curve closing the distal end so as to decrease stress concentrated at the turn.
 2. The solid oxide fuel cell structure as claimed in claim 1, wherein each of the at least two air paths has a semi-spherical contour.
 3. The solid oxide fuel cell structure as claimed in claim 1, wherein the at least two air paths are arranged alternately.
 4. The solid oxide fuel cell structure as claimed in claim 2, wherein the at least two air paths are arranged alternately.
 5. The solid oxide fuel cell structure as claimed in claim 1, wherein the continuous curve is a section of quadric surface.
 6. The solid oxide fuel cell structure as claimed in claim 1, wherein the continuous curve is a section of camber.
 7. The solid oxide fuel cell structure as claimed in claim 1, wherein the continuous curve is a section of spherical surface.
 8. The solid oxide fuel cell structure as claimed in claim 1, wherein the continuous curve is a section of parabolic quadratic surface.
 9. The solid oxide fuel cell structure as claimed in claim 1, wherein the continuous curve has a slope with a continuous value.
 10. The solid oxide fuel cell structure as claimed in claim 2, wherein the continuous curve has a slope with a continuous value.
 11. The solid oxide fuel cell structure as claimed in claim 3, wherein the continuous curve has a slope with a continuous value.
 12. The solid oxide fuel cell structure as claimed in claim 4, wherein the continuous curve has a slope with a continuous value.
 13. The solid oxide fuel cell structure as claimed in claim 5, wherein the continuous curve has a slope with a continuous value.
 14. The solid oxide fuel cell structure as claimed in claim 6, wherein the continuous curve has a slope with a continuous value.
 15. The solid oxide fuel cell structure as claimed in claim 7, wherein the continuous curve has a slope with a continuous value.
 16. The solid oxide fuel cell structure as claimed in claim 8, wherein the continuous curve has a slope with a continuous value. 